The ModType tag tells MCU what to do with a Mod once it has downloaded it. There are currently 8 different valid types, but for modern packs, you usually only need to consider a few:

Regular – A regular mod, this is a jar/zip file that is placed in the /mods folder once it is downloaded.

Extract – A zip file that will dump its contents into the /mods folder. If you specify the attribute inRoot=’true’, then it will decompress the zip into the pack’s base directory. This is useful for providing many little files (like configs).

Litemod – A liteloader mod, this goes in the /mods folder with a .litemod extension.

The other valid types are:

Coremod – An old style mod that belongs in the /coremods folder.

Jar – An old style (or just weird) mod that still needs to be installed directly in the minecraft jar file.

Library – A library file that goes into the /libs folder and is added to the java classpath at launch. This is usually for things that need to load themselves (like mod loaders).

Override – An existing mod with the same id defined earlier in the pack will be updated with any tags provided in this entry.

Removal – An existing mod with the same id defined earlier in the pack will be removed. This is useful when you are Importing another pack and don’t want to include everything it provides.